A sign is displayed in an unmarked Serious Fraud Office vehicle parked outside a building, in Mayfair, central London March 9, 2011. REUTERS/Andrew Winning

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By Kirstin Ridley and Steve Slater

LONDON (Reuters) - The UK Serious Fraud Office (SFO) is pressing for a civil lawsuit against Barclays by former senior investment banker Richard Boath to be heard in private to avoid prejudicing its investigation into the bank's 2008 emergency fundraising.

Boath, one of a number of former top Barclays executives questioned by the SFO in a criminal investigation over the bank's fundraising from Gulf investors during the credit crisis, is suing Barclays in a pay dispute, according to court listings.

The SFO said it had applied to the East London Employment Tribunal to either impose privacy on the proceedings or to ensure that Boath and Barclays' legal representatives do not refer to the contents of an SFO interview with Boath in open court when the case kicks off in earnest next week.

The SFO application is due to be discussed in court on Nov. 21. No further details were immediately available.

The agency has said it expects to decide whether to charge Barclays and former executives early next year in its criminal inquiry into the bank's financial arrangements with Qatar, that included a Barclays' loan to the Gulf state.

The investigation centers on commercial agreements between Barclays and Qatari investors as part of a capital raising to raise a total of about 12 billion pounds ($15 billion) at the height of the credit crisis.

Barclays' emergency fundraising, which allowed the bank to become one of the few British lenders to sidestep a state bailout, has also triggered a separate civil lawsuit by businesswoman Amanda Staveley.

Her private equity group PCP Capital Partners is claiming around $1 billion in damages for alleged fraudulent misrepresentation.

That case, which is due to come to trial in January 2018 if it is not settled, hinges on the terms that Qatari and Abu Dhabi investors received for participating in a cash call by Barclays to raise around 7 billion pounds in 2008.

Staveley, who put together a syndicate of Abu Dhabi investors in October 2008, has alleged in court documents that Barclays made an undisclosed $3 billion loan to Qatar shortly before completion of the October 2008 capital raising.

Barclays said in 2013 that British authorities were investigating the bank and four current and former senior employees over the fundraising.

Sources familiar with the matter have said Boath, who was co-head of global finance in EMEA at the time of the capital raising, has been interviewed alongside former chief executives Bob Diamond and John Varley, former finance director Chris Lucas and former tax advisory boss Roger Jenkins among others.

Boath, most recently Barclays' chairman of the financial institutions group, left the bank in March. He has not publicly commented on the investigation.